JPH0617610A - Valve drive for internal combustion engine - Google Patents

Abstract

(57) [Summary] (Correction) [Purpose] In a valve train of an internal combustion engine, a slip between a cam and a cam follower is reduced to further effectively reduce a friction therebetween. A valve lifter 9 is provided between an intake valve 4 and a cam 3 on a camshaft 2 in an internal combustion engine. Cam 3
The cam follower 15 is interposed between the valve lifter 9 and the valve lifter 9, and the cam follower 15 can be rotated on the valve lifter 9 by forming a bearing. The cam follower 15 is arranged on the valve lifter 9 while being inclined by an angle θ so that the end portion 15a of the cam follower 15 on the side in the rotation direction A of the cam 3 approaches the cam 3. Therefore,
Since the cam follower 15 is inclined, the rotational torque of the cam 3 effectively acts on the cam follower 15 in a direction close to the vertical direction, and the cam follower 15 easily rotates.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a valve operating system provided for opening and closing intake and exhaust valves of an internal combustion engine.

[0002]

2. Description of the Related Art Conventionally, as a technique of this type, for example, in Japanese Utility Model Laid-Open No. 2-61102, an outer shim (cam follower) interposed between a valve lifter having a cylindrical shape with a lid and a cam on a camshaft is used as a valve lifter. It is disclosed that it is rotatable above. That is, in this conventional technique, the guide portion is provided so as to protrude from the center of the upper wall portion of the valve lifter, and the corresponding recess is provided at the center of the cam follower. The cam follower is supported by the upper wall portion of the valve lifter with the recess fitted in the guide portion. Further, the cam is arranged in contact with a portion slightly displaced from the center of the upper surface of the cam follower. Therefore, when the cam is rotated, a rotational force is applied to the cam follower accordingly, and the cam follower is rotated about the guide portion. As a result, the friction between the cam follower and the cam has been reduced.

[0003]

However, in the above-mentioned prior art, although the friction between the cam follower and the cam is reduced by making the cam follower rotatable, inevitably there is a problem between the cam and the cam follower. There was some slippage. Therefore, it is not sufficient to reduce the friction between the cam and the cam follower.

The present invention has been made in view of the above-mentioned circumstances, and an object thereof is to provide a cam follower interposed between a cam and a valve lifter so that the cam follower can rotate as the cam rotates. An object of the present invention is to provide a valve train for an internal combustion engine that can reduce slippage between the cam follower and friction between the cam follower and the cam follower more effectively.

[0005]

In order to achieve the above object, in the present invention, a valve lifter provided between an intake / exhaust valve in an internal combustion engine and a cam on a camshaft, and a cam and a valve lifter. Is intervened between
In a valve train of an internal combustion engine having a cam follower rotatably provided on the valve lifter, the cam follower is tilted on the valve lifter so that the end of the cam follower on the rotation direction side of the cam is close to the cam. It is arranged.

[0006]

With the above arrangement, since the cam follower is inclined so that the end of the cam follower in the rotational direction of the cam is close to the cam, the rotational torque of the cam is almost perpendicular to the cam follower. The cam follower works effectively and the cam follower easily rotates.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the valve operating system for an internal combustion engine according to the present invention will be described in detail below with reference to FIGS.

FIG. 1 is a sectional view showing a valve operating system in this embodiment. Above a cylinder head 1 which constitutes an internal combustion engine, a cam shaft 2 which is rotationally driven in conjunction with a crank shaft (not shown) is arranged, and on the cam shaft 2, a cam composed of a basic circle 3a and a nose 3b. Three
Are provided integrally. Immediately below the cam 3, large and small guide holes 5 and 6 are formed in the cylinder head 1 in series in the up-down diagonal direction corresponding to the intake valve 4 as a valve for intake and exhaust, and both guide holes 5 and 6 are formed. A cavity 7 is formed between them. An intake port 8 that is opened and closed by an intake valve 4 is formed in the cylinder head 1.

In the above-mentioned upper guide hole 5, a direct hitting type valve lifter 9 having a cylindrical shape with a lid is attached so as to be slidable in the vertical direction. A stem guide 11 for slidably guiding the stem 10 extending from the intake valve 4 is attached to the lower guide hole 6. In addition, the cavity 7
A washer 12 is attached to the bottom wall 7a of the above with the stem guide 11 as the center. Then, on the upper portion of the stem 10 that extends upward through the stem guide 11, the kotak 13
Also, the retainer 14 is attached, and the upper end of the stem 10 is in contact with the bottom wall 9 a of the valve lifter 9. On the other hand, a circular recess 9b is formed on the upper surface of the valve lifter 9,
In the recess 9b, a disc-shaped cam follower 15 interposed between the cam 3 and the valve lifter 9 is rotatably arranged. Then, around the stem 10, the retainer 1
A coil spring 16 is mounted between the washer 4 and the washer 12, and the spring 16 closes the intake valve 4 and the valve lifter 9 together with the cam follower 15 to the cam 3, that is, the intake valve 4 closes the intake port 8. Biased in the direction.

In this embodiment, in order to smoothly rotate the cam follower 15 on the valve lifter 9, a bearing is provided between the two members 9 and 15, and the cam follower 15 is arranged to be inclined with respect to the cam 3.

That is, as shown in FIG. 2, the valve lifter 9
A bearing recess 17 is formed in the center of the recess 9b. A plurality of balls 1 are formed around the bearing recess 17.
A recessed groove 19 accommodating 8 is formed. Further, the bottom surface of the recess 9b is formed so as to be inclined by a predetermined angle θ with respect to the central axis L of the valve lifter 9. In this embodiment, the angle θ is set to about “1 °”. On the other hand, the cam follower 15 is formed to have a uniform thickness, and the outer peripheral surface is obliquely cut so that the cam follower 15 is fitted into the recess 9b in alignment with the inclination angle θ of the recess 9b. Further, a shaft 20 projecting downward is formed in the center of the lower surface of the cam follower 15 so as to be parallel to the central axis L of the valve lifter 9, and around the shaft 20, a concave groove corresponding to each ball 18 described above is formed. 21 is formed. Then, as shown in FIG. 1, the cam follower 15 is provided with the recess 9 of the valve lifter 9.
With the cam follower 15 fitted in the shaft b,
It is possible to rotate around. Around the shaft 20, a plurality of balls 18 are interposed between the valve lifter 9 and the cam follower 15. Furthermore, the cam follower 15
The end portion 15a of the cam 3 in the rotation direction A side of the cam 3 is
So that the cam follower 15 is close to the valve lifter 9
It is arranged so as to be inclined by the angle θ above.

In addition, in this embodiment, a rotational force is applied to the cam follower 15 as the cam 3 rotates. That is, as shown in FIG. 3, when the cam follower 15, the cam 3 and the like are viewed from above, the cam 3 is arranged so as to be displaced from the center of the cam follower 15. That is, the center line L1 of the cam 3 in the width direction is arranged so as to deviate from the center line L2 of the cam follower 15 along the axial direction of the cam shaft 2 by a predetermined distance W.

In this embodiment, an oil passage (not shown) is formed in the camshaft 2 in order to lubricate the cam 3 and the cam follower 15, and the lubrication between the both 3 and 15 is performed through the oil passage. Oil is supplied.

Next, the operation of the valve operating device constructed as described above will be described. Now, in FIG. 1, when the cam 3 is rotated in the rotation direction A along with the rotation of the camshaft 2, the cam 3 follows the cam profile while following the cam profile.
Sliding contact with 5. As a result, the valve lifter 9 and the intake valve 4 together with the cam follower 15 are periodically pushed down against the biasing force of the coil spring 16, and the intake port 8 is opened and closed.

At this time, the cam 3 is replaced by the cam follower 15
Since the cam follower 15 is rotated while being slidably contacted with the cam follower 15 in a state of being displaced from the center, a rotational force in a direction indicated by an arrow B in FIG. 3 is applied, and the cam follower 15 is rotated. or,
In this embodiment, since the bearing between the valve lifter 9 and the cam follower 15 is formed by the shaft 20, the plurality of balls 18, etc., the cam follower 15 is smoothly rotated, and the cam follower 15 can be rotated at high speed. Since the cam follower 15 can be rotated at a high speed, the amount of lubricating oil supplied between the cam 3 and the cam follower 15 increases, and the boundary lubrication state is avoided.
The oil film formed between 15 can be thickened. According to the experimental results, compared to the case where the cam follower is fixed,
In this embodiment, the thickness of the oil film between the cam 3 and the cam follower 15 could be "about 1.7 times". As a result, the friction between the cam 3 and the cam follower 15 can be reduced, and the fuel economy of the internal combustion engine can be improved.

Moreover, in this embodiment, the cam follower 1
The cam follower 15 is inclined so that the end portion 15a of the cam 3 on the side of the rotation direction A of the cam 3 approaches the cam 3. Therefore, the rotational torque of the cam 3 effectively acts on the cam follower 15 from the nose 3b in a direction nearly perpendicular to the cam follower 15, and the cam follower 15 easily rotates. As a result, it is possible to reduce slippage that remains between the cam 3 and the cam follower 15 as much as possible. Further, thereby, the friction between the cam 3 and the cam follower 15 can be further effectively reduced, and by extension, the cam 3 and the cam follower 15 can be reduced.
The life of can be extended. Further, since the rotational torque of the cam 3 acts on the cam follower 15 in a direction close to the vertical direction, the stress in the cam follower 15 acts in a direction close to the vertical direction, and the load on the shaft 20 of the cam follower 15 is reduced and its life is reduced. Can be extended.

In addition, as an additional effect of thickening the oil film between the cam 3 and the cam follower 15, it is possible to reduce the idle speed of the internal combustion engine. Further, the curvature of the nose 3b of the cam 3 can be set smaller. Furthermore, the spring load (biasing force) of the coil spring 16 can be increased, and the sealing performance when the intake valve 4 is closed can be improved. Alternatively,
In order to secure a similar film thickness ratio (ratio of the minimum oil film thickness to the surface roughness), the surface roughness can be made relatively rough, and the cam 3 and the cam follower 15 can be processed by that amount. You can save time.

The present invention is not limited to the above-described embodiment, but may be implemented as follows with a part of the configuration appropriately changed without departing from the spirit of the invention. (1) In the above-described embodiment, in order to make the cam follower 15 rotatable on the valve lifter 9, a bearing is provided between the valve lifter 9 and the cam follower 15 by the shaft 20 and a plurality of balls 18, etc. A roller may be provided between the gaps.

(2) In the above embodiment, the stem 10 of the intake valve 4 is embodied when it is arranged in the up and down diagonal direction, but it can be embodied when the stem is arranged in the vertical direction.

(3) In the above embodiment, the valve operating device corresponding to the intake valve 4 is used, but a valve operating device corresponding to the exhaust bubbling may be used.

[0021]

As described above in detail, according to the present invention, in the cam follower interposed between the cam and the valve lifter, the cam follower is rotatable as the cam rotates.
Since the cam follower is inclined so that the end of the cam follower on the rotational direction side of the cam approaches the cam,
The rotation torque of the cam effectively acts on the cam follower in a direction nearly perpendicular to the cam follower to facilitate rotation of the cam follower, and slip between the cam and the cam follower can be reduced.
Therefore, it is possible to effectively reduce the friction between the cam and the cam follower, which is an excellent effect.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a valve gear in an embodiment embodying the present invention.

FIG. 2 is an enlarged cross-sectional view showing an assembled state of a valve lifter and a cam follower and a configuration of forming a bearing between them in an embodiment.

FIG. 3 is a plan view showing a state in which a cam follower, a cam, and the like are viewed from above in one embodiment.

[Explanation of symbols]

2 ... Cam shaft, 3 ... Cam, 4 ... Intake valve, 9 ... Valve lifter, 15 ... Cam follower, 15a ... End, θ ...
Angle, A ... Direction of rotation.

Claims (1)

[Claims] 1. A valve lifter provided between a valve for intake and exhaust of an internal combustion engine and a cam on a cam shaft, and a valve lifter interposed between the cam and the valve lifter and rotatably provided on the valve lifter. In a valve operating system for an internal combustion engine having a cam follower, the cam follower is arranged so as to be inclined on the valve lifter so that an end of the cam follower on the rotational direction side of the cam is close to the cam. A valve operating system for an internal combustion engine, comprising: